1. Field of the Invention
The present invention relates to an image recorder for directing an optical beam onto an image recording material such as a plate mounted on a drum to record an image on the image recording material.
2. Description of the Background Art
The process of feeding an image recording material such as a plate to an image recorder includes positioning the image recording material in a first direction perpendicular to a second direction in which the image recording material is fed, and then transporting the image recording material to a mechanism, such as a drum, for holding the image recording material or to a mechanism, such as a punch unit, for punching the image recording material. The positioning operation is of various types: adjustment (referred to as centering) of the image recording material with respect to the center of the image recording material as seen in the first direction, and adjustment (referred to as side edge registration) thereof with respect to one side edge of the image recording material.
Registration in a conventional image recorder, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-56482 is carried out in a manner to be described below. A pair of side-to-side adjustment bearings are prepared which are movable toward and away from each other. With an image recording material placed between the pair of side-to-side adjustment bearings, the pair of side-to-side adjustment bearings are moved toward each other to press opposite side edges of the image recording material.
In the conventional image recorder, only one image recording material has been mounted on the drum. In recent years, however, there has been a demand to allow selection of the number of plates to be mounted on the drum for purposes of improvements in productivity and serviceability of an image recorder. Also, there has been another demand to increase the range of sizes of usable image recording materials. Such diversification of the plates for use in the image recorder, however, creates a need to make various changes in the reference position of side-to-side adjustment. Merely providing a plurality of pairs of conventional side-to-side adjustment units presents a problem such that the plurality of pairs of side-to-side adjustment units come into competition with each other depending on the number and size of plates.